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Abstract

Multi-modal hard x-ray imaging sensitive to absorption, refraction, phase and scattering contrast is demonstrated using a simple setup implemented with a laboratory source. The method is based on selective reflection at the edge of a mirror, aligned to partially reflect a pencil x-ray beam after its interaction with a sample. Quantitative scattering contrast from a test sample is experimentally demonstrated using this method. Multi-modal imaging of a house fly (Musca domestica) is shown as proof of principle of the technique for biological samples.

Figures (3)

Schematic of the experimental setup (not to scale). X-rays, after interacting with the sample, illuminate the mirror edge, aligned to partially obscure a given pixel row of the detector (Id). Photons that strike the mirror are reflected onto a different pixel row (Ir). Weak scattering occurring at the sample may be detected around the direct beam direction, especially in a pixel row that is covered by the mirror shadow (Is), generating a dark field image. For the data shown in this paper we used z1 = 100 mm and z2 = 210 mm. The mirror tilt angle was 3.3 mrad from the optic axis producing a transverse displacement of the reflected beam of about 1.5 mm at the detector position.

(a) Dark field x-ray image of a stack of optical paper tissues with variable thickness. The leftmost region corresponds to one paper sheet while the rightmost region corresponds to scattering from a stack of 6 optical paper sheets. Image data have been background subtracted, the said background corresponding to the intensity image measured in the absence of the paper. (b) Plot of the average counts in regions of equal thickness against the paper stack thickness (filled diamonds). The red solid line gives the linear fit to the data.

Multi-modal x-ray imaging of the abdomen of a house fly. (a) Attenuation image, (b) Refraction angle image, (c) Phase image, (d) Scatter (dark-field) image and (e) Absorption-free image (see text for details). The linear structures on both sides of the sample are the edges of a kapton foil, rolled to form a conical shape, used to hold the sample in place during the scan.